Breivik, a white supremacist who wanted to bring about a fascist revolution through violent means, detonated a car bomb outside the prime minister's office in Oslo, killing eight, before driving to Utoeya island and shooting 69 people at a Labour Party youth camp on July 22, 2011.
On Thursday morning, Prime Minister Erna Solberg addressed a memorial service attended by survivors and relatives of the victims, political leaders and Norway's Crown Prince and Crown Princess.
"It hurts to think back to that dark day in July ten years ago. Today, we mourn together. Today, we remember the 77 that never came home," Solberg said.
The memorial was held in central Oslo outside what was once the prime minister's office - an empty shell since the attack due to disagreements over how to rebuild it. People passing by beyond the secured perimeter stopped to listen and some hugged as the names of the victims were read out.
Breivik, 42, is serving a 21-year sentence, which can be prolonged indefinitely if he is deemed a continued threat to society.
Debate over the attacks has shifted over the years. Survivors, many of whom were teenagers at the time, are now determined to confront the far-right ideology which was a catalyst for the attack.
This is a departure from Norway's response at the time, which emphasised unity and consensus, with Jens Stoltenberg, the Labour Party prime minister at the time, calling Breivik's actions attacks on Norway and democracy.
"Ten years later, we need to speak the truth. We have not stopped the hate. Right-wing extremism is still alive," said Astrid Hoem, leader of the Labour Party youth organisation AUF, and a survivor of the Utoeya attack, at the memorial event.
"The terrorist was one of us. But he does not define who we are - we do," Hoem said.
After ten years, it was time to clearly reject racism and hate once and for all, Hoem said. "Because if we do this now, we might be able to keep our promise of 'Never again July 22'."
At a service in the Oslo Cathedral, Stoltenberg, now NATO Secretary-General, pointed to recent incidents of far right violence, including continued death threats against the attacks' survivors and the vandalism of a memorial to 2001 teenage hate crime victim Benjamin Hermansen, with the slogan "Breivik was right" earlier this week.
"Ten years ago we met hate with love. But the hate is still there," Stoltenberg said. "Again and again we are reminded that democracy has not been won once and for all. We need to fight for it day after day."
Following the service, at 1210 CET (1010 GMT) church bells across the country rang out for five minutes.
Ten years ago, the Norwegian public expressed their sorrow by red roses - a symbol of the Labour Party- and other flowers before the cathedral and on Thursday, passers-by are again bearing roses to the same place in tribute. The victims of Utoeya came from all parts of the country and memorial services are being held across Norway, with people also laying down flowers in other cities.
Later, there will also be a ceremony on Utoeya and the day will conclude with an evening ceremony in Oslo during which King Harald will speak.
A group of survivors have set up a Twitter account @aldriglemme (Never forget) to re-post tweets about the attack as they appeared 10 years ago.